Offaly Castles Project
For details on all 200 castle sites in Offaly see www.archaeology.ie - click on Archaeological Survey Database and you can search by location or monument type.
There has been collaberative work over the past number of years between the Archaeological Survey of Ireland and the Heritage Office doing further research on the castles of County Offaly. Two pdfs on Ballindarra and Ballyboy castles are available.
Ballindarra Castle Co Offaly 3 MB
Ballyboy Castle, Co. Offaly 6 MB